The impact of polishing on germanium-on-insulator substrates

We prepared germanium-on-insulator (GOI) substrates by using Smart-Cut™ and wafer bonding technology. The fabricated GOI is appropriate for polishing due to a strong bonding strength (2.4 MPa) and a sufficient bonding quality. We investigated mechanical polishing and chemical—mechanical polishing (CMP) systematically, and an appropriate polishing method—mechanical polishing combined with CMP—is obtained. As shown by AFM measurement, the RMS of GOI after polishing decreased to 0.543 nm. And the Ge peak profile of the XRD curve became symmetric, and the FWHM is about 121.7 arcsec, demonstrating a good crystal quality.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Spin-on doping of germanium-on-insulator wafers for monolithic light sources on silicon

High electron doping of germanium (Ge) is considered to be an important process to convert Ge into an optical gain material and realize a monolithic light source integrated on a silicon chip. Spin-on doping is a method that offers the potential to achieve high doping concentrations without affecting crystalline qualities over other methods such as ion implantation and in-situ doping during material growth. However, a standard spin-on doping recipe satisfying these requirements is not yet available. In this paper we examine spin-on doping of Ge-on-insulator (GOI) wafers. Several issues were identified during the spin-on doping process and specifically the adhesion between Ge and the oxide, surface oxidation during activation, and the stress created in the layers due to annealing. In order to mitigate these problems, Ge disks were first patterned by dry etching followed by spin-on doping. Even by using this method to reduce the stress, local peeling of Ge could still be identified by optical microscope imaging. Nevertheless, most of the Ge disks remained after the removal of the glass. According to the Raman data, we could not identify broadening of the lineshape which shows a good crystalline quality, while the stress is slightly relaxed. We also determined the linear increase of the photoluminescence intensity by increasing the optical pumping power for the doped sample, which implies a direct population and recombination at the gamma valley.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Room-temperature direct bonding of germanium wafers by surface-activated bonding method

This paper reports the mechanical and electrical characteristics of Ge/Ge interfaces prepared by room-temperature surface-activated bonding (SAB). Bonded Ge/Ge wafer pairs with high bonding strength equivalent to that of the bulk material were achieved without any heat treatment. It was found that the bonding of Ge wafers was not sensitive to the background vacuum pressure in a wafer-bonding chamber compared with the bonding of Si wafers. The current–voltage characteristics and microstructures of bonded interfaces formed by SAB and low-temperature plasma activation bonding (PAB) were compared. It was demonstrated that junctions with very low resistivity can be obtained by SAB at room temperature

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Characteristics of Germanium-on-Insulators Fabricated by Wafer Bonding and Hydrogen-Induced Layer Splitting

There is considerable interest in germanium-on-insulator (GeOI) because of its advantages in terms of device performance and compatibility with silicon processing. In this paper, fabricating GeOI by hydrogen-induced layer splitting and wafer bonding is discussed. Hydrogen in germanium exists in molecular form and is prone to outdiffusion, resulting in a storage-time dependence of blistering. In contrast to the case of silicon, little effect of substrate doping on blistering is observed in germanium. Hydrogen implantation in germanium creates both {100}- and {111}-type microcracks. These two types of platelets are located in the same region for (111)-oriented wafers, but in different zones for (100) samples. This variation in distribution explains the smoother splitting of (111) surfaces than that of (100) surfaces. Hydrogen implantation also introduces a significant concentration of charged vacancies, which affect dopant diffusion in the transferred germanium film. Boron, with a negligible Fermi-level dependence, shows an identical diffusion profile to that of bulk germanium. In contrast, phosphorus diffusion is enhanced in the fabricated GeOI layers. These results also shed light on the understanding of dopant diffusion mechanisms in germanium.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Effects of the chemical bonding on the optical and mechanical properties for germanium carbide films used as antireflection and protection coating of ZnS windows

Germanium carbide (Ge1−xCx) films have been prepared by RF reactive sputtering a pure Ge(111) target at different flow rate ratios of CH4/(CH4+Ar) in a CH4/Ar mixture discharge, and it has been found that the composition, chemical bonding, optical and mechanical properties of Ge1−xCx films are remarkably influenced by the flow rate ratio of CH4/(CH4+Ar). The effects of the chemical bonding on the optical and mechanical properties of the Ge1−xCx films have been explored. In addition, an antireflection Ge1−xCx double-layer coating deposited on both sides of the ZnS substrate wafer has been developed for application as an infrared window. It is shown that the transmittance in the wavelength region between 8 and 12 µm and the hardness of the ZnS substrate have been significantly improved by the double-layer coating.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com